@p maximum_input_line_length = infinity

@$@<If To While Lido@>@{@-
SYMBOL Stmt: count: int;
SYMBOL Stmt COMPUTE
	SYNT.count = 1;
END;

CLASS SYMBOL CountStmts: count: int;
CLASS SYMBOL CountStmts COMPUTE
    SYNT.count = 
        CONSTITUENTS Stmt.count 
	WITH (int, ADD, IDENTICAL, ZERO);
END;

SYMBOL IfTrue INHERITS CountStmts END;
SYMBOL IfFalse INHERITS CountStmts END;

SYMBOL IfStmt: iftowhileok, iftowhilebranch: int;
SYMBOL IfStmt COMPUTE
    SYNT.iftowhileok = 
	OR(EQ(CONSTITUENT IfTrue.count, 0), 
	   EQ(CONSTITUENT IfFalse.count, 0));

    SYNT.iftowhilebranch =
	IF (EQ(CONSTITUENT IfTrue.count, 0), 2, 1);

    IF (THIS.iftowhileok,
	VLContextedit(_currn, "If -> While", 
	    VLLIST3("::Change", "pWhileStmt", 
                THIS.iftowhilebranch)),
	VLContextedit(_currn, "If -> While", 
	    VLLIST2("::CDlg::Information", 
                "Cannot do that,\nYou would lose data!")));
		
END;		

SYMBOL WhileStmt
COMPUTE
    VLContextedit(_currn, "While -> If", 
	VLLIST3("::Change","pIfStmt", 1));
END;

@}

@O@<iftowhile.view1.sl@>@{@-
@<If To While Lido@>
@}

@O@<iftowhile.tcl@>@{@-
proc ::Change {prod index whilestmt} {

	# Get Pointers to the interesting data
	set whileexpr [lindex [::vl::getDesc $whilestmt] 0]
	set expr [::vl::getDesc $whileexpr]
	set whilebody [lindex [::vl::getDesc $whilestmt] $index]
	set stmts [::vl::getDesc $whilebody]

	# Create a new pIfStmt
	set stmt [::vl::create $::vl::prod($prod)]
	set ifstmt [::vl::getDesc $stmt]
	set ifexpr [lindex [::vl::getDesc $ifstmt] 0]
	set iftrue [lindex [::vl::getDesc $ifstmt] 1]

	# Move the Expression and the Statement
	::vl::extract $stmts
	::vl::insert $iftrue 0 $stmts 1
	::vl::extract $expr
	::vl::insert $ifexpr 0 $expr 1

	# Search replacement position
	set stmt_while [::vl::getFather $whilestmt]
	set stmts_while [::vl::getFather $stmt_while]
	set pos [lsearch -exact [::vl::getDesc $stmts_while] $stmt_while]

	# Replace it.
	::vl::insert $stmts_while $pos $stmt 1
}
@}